Method for establishing a local media connection in a communication system

ABSTRACT

The present invention relates to a method for deciding, in an IP-based communication system, whether a local media/media release is allowed between a first and at least a second terminal. The method is characterized in that the decision is based on information established by an application server in an multimedia core network. The present invention further also relates to a session border controller unit, a session border controller, an application server and a computer program product for performing said method.

TECHNICAL FIELD

The present invention relates in general to a method for establishing alocal media connection in a telephone communication system, and inparticular to a method for deciding whether or not a local mediaconnection should be used between two terminals in a telephonecommunication system.

The present invention further relates to a session border controllerunit, a session border controller, an application server, a multimediacore network and a computer program product.

BACKGROUND

Within an IP based communication system comprising an access network toan external IP based communication network, such as, for example, theInternet or IMS (IP Multimedia Subsystem), Session Border Controllers(SBC) are usually located in between the access network and IP basedcommunication core networks. The SBCs are arranged to provide access andinterconnections for terminals in the access network to the IP-basedcommunication core networks. The SBCs may also, by creating terminationsor anchoring points in a media proxy for a call between two terminals,provide operators with the ability to monitor various call parameters,such as, for example, call length, call services etc.

However, SBCs may further be arranged to refrain from anchoring mediaplane traffic in the SBCs between two terminals. This allows the mediaplane traffic of the call to float directly between the two terminals inthe access network. This functionality in a telephone communicationssystem may be referred to as local media or media release connection.

A local media or media release connection between two terminals may beused, for example, in company internal networks or other organizationalstructures, in order to achieve a more efficient usage of availablebandwidth. It may also be used to avoid occupying unnecessary resourcesby having media plane streams from the access network also runningthrough other network nodes in the IP based communications core network.

This may also be referred to as hair pinning or anchoring media streamsof the access network in the IP based communications core network.

Before establishing a local media or media release connection betweentwo terminals in the access network, the SBCs must independently make adecision whether or not a local media or media release connection isallowed between the calling terminal and the called terminal. Therefore,the SBCs must be configured and updated with user information aboutwhich terminals in the access network that are allowed to communicatewith each other using a local media or media release connection.

This provides SBCs with a high degree of complexity. It also makesupdating and adding to the user configuration information atime-consuming and arduous task. In the case of multiple SBCs, it alsofollows that each of the SBCs has to be individually programmed with theuser configuration information.

SUMMARY

A problem to which the present invention relates is the problem ofreducing the complexity of a network node in a session border controllerthat allows local media or media release connection in a communicationsystem.

This problem is addressed by a method for deciding whether a local mediaconnection should be established in an access network of an IP-basedcommunication system between a first and at least a second terminallocated within said access network, wherein said access network isconnected to a session border controller providing access to anmultimedia core network, characterized in that said decision is made bysaid session border controller based on information established by andreceived from an application server in said multimedia core network.

By having the user configuration in an application server, a significantpart of the complexity of the networks nodes in the session bordercontroller is removed, and allows the session border controller to befocused more on its dedicated tasks. The application server of anmultimedia core network is arranged to provide operators with thepossibility to easily handle users and user group information, and istherefore provides a more suitable and flexible solution for allowing alocal media or media release connection in an access network.

An advantage of the above described invention, besides solving theproblem addressed above, is that it enables system operators andadministrators to provide a more flexible and easier local media servicefor its customers.

A further advantage of the above described invention is that it enablesa local media or media release between two terminals, wherein at leastone of the terminals is located in a visited network.

The method may further include having a session border controller unitthat, if the message from said application server indicates that a localmedia connection is allowed between said first and at least secondterminal, establishes a local media connection between said first and atleast second terminal.

The method may further include having a session border controller unitthat, if the message from said application server indicates that a localmedia connection is not allowed between said first and at least secondterminal, establishes a communication channel between said first and atleast second terminal anchored in a media proxy in said session bordercontroller.

A further advantage of the above described invention is that it reducesthe use of system resources in the core networks of a communicationsystem, by making it possible for an operator to more frequently andsimpler perform updates of the user configuration information. Sincemore local media connections then may be established in the accessnetwork the present invention also reduces delay and packet loss in acommunication system.

The object of the present invention is further achieved by a sessionborder controller unit for deciding whether a local media connectionshould be established in an access network of an IP-based communicationsystem between a first and at least a second terminal located withinsaid access network, wherein said session border controller is connectedto said access network and an multimedia core network, characterized inbeing arranged to make said decision based on information established byand received from an application server in said multimedia core network.

The object of the present invention is also achieved by a session bordercontroller comprising a session border controller unit according to theabove.

The object of the present invention is also achieved by an applicationserver in a multimedia core network, characterized in being arranged toprocess information in order to establish whether a local mediaconnection is allowed between a first and at least a second terminal inan access network of an IP-based communication system.

The object of the present invention is also achieved by an multimediacore network comprising an application server according to the above.

The object of the present invention is also achieved by a computerprogram product for use in a session border controller unit, whichcomprises computer readable code means, which when run in the sessionborder controller unit, causes said session border controller unit, tomake a decision whether a local media connection between a first and atleast a second terminal should be established in an access network basedon information established by and received from an application server insaid multimedia core network.

Further advantageous embodiments of the method, the session bordercontroller unit, the session border controller, the application server,the IMS network and the computer program product are set forth in thedependent claims, which correspondently describe further advantageousembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and further advantages of the present inventionwill become apparent by reading this description in conjunction with theaccompanying drawings, in which like reference numerals refer to likeelements and in which:

FIG. 1 is a block diagram illustrating an IP based communication systemaccording to prior art.

FIG. 2 is a block diagram illustrating an IP based communication systemaccording to the present invention.

FIG. 3 is a flowchart illustrating an exemplary operation of a sessionborder controller and network nodes according to the present invention.

FIG. 4 is a signalling diagram illustrating in more detail thesignalling between terminals, session border controller and networknodes according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates an IP based communication system according to priorart. In the following the term IP based communication system will beused in reference to any communication system capable of communicatingusing the Internet Protocol (IP) such as, for example, transit networks(the Internet, Intranets, Local Area Networks (LANs), Wide Area Networks(WANs) and Frame Relay, ATM or X.25 based transit networks etc.) and/ormobile radio communication networks such as, for example, UTRAN(Universal Terrestrial Radio Access Network), GERAN (GSM/EDGE RadioAccess network) and/or EPS/SAE (Evolved Packet System/SystemArchitecture Evolution). The term terminal will be used to denote anycommunication terminal capable of communicating within such acommunication system, or the like, using the Internet Protocol (IP),such as, for example, VoIP/SIP telephones, mobile terminals, laptops,desktop computers, palm pilots etc.

The term local media connection is hereinafter, in the description andsubsequent claims, used to refer to local media or media release or thelike.

In FIG. 1, the terminals UE A and UE B are located within an accessnetwork 1 of an IP based communications system. The access network 1 isarranged to communicate with a Session Border Controller (SBC) 3. TheSBC 3 provides access and interconnections for terminals in the accessnetwork 1 to IP-based communication core networks, such as, multimediacore networks, and in this case, particularly to the IMS core network 2.The SBC 3 may comprise a Proxy Call Session Control Function (P-CSCF) 4and a Media Proxy (MP) 5. The MP 5 may commonly also be referred to as aCore-Border Gateway Function (C-BGF). Although not shown in FIG. 1 or 2,a Service Policy Decision Function (SPDF) may also be located betweenthe P-CSCF 4 and the MP 5 in the SBC 3. In the SBC 3, the signallingfunctions can occur on a separate hardware platform than the media relayfunctions, that is, the P-CSCF 4 may be separated from the MP 5 andphysically be located elsewhere.

The IMS core network 2 in FIG. 1 illustrates a simplified example of anIMS core network architecture. In FIG. 1, the IMS core network 2 isshown comprising the network nodes, Serving Call Session ControlFunctions (S-CSCF) 6, Applications Servers (AS) 7, a Media GatewayController (MGC) 8, a Media Gateway (MG) 9, a Media Resource FunctionController (MRFC) 10, a Media Resource Function Processor (MRFP) 11 andHome Subscriber Service (HSS) 12. It should be noted that the IMS corenetwork 2 may also be said to comprise further nodes and entities, butis for the sake of simplicity and relevance to the present invention notdescribed in further detail herein. More information about IMS, the IMSstandards and the different types of nodes available therein can befound in, for example, the TISPAN specifications ETSI ES 282.007 andETSI ES 283.003, and the 3GPP specification TS 23.002. Anotherspecification relevant to the present invention is the TISPANspecification ETSI ES 282.003.

According to prior art, as the terminal UE A attempts a call to theterminal UE B, a SIP (Session Initiation Protocol) invite message withan SDP (Session Description Protocol) offer will be sent from theterminal UE A to a P-CSCF 4 in the SBC 3 through the control plane pathA. It should be noted that the P-CSCF 4 in the SBC 3 may also be anAccess Application Level Gateway (A-ALG), whereby the P-CSCF 4 then maybe located in the IMS core network 2. However, the A-ALG may implementparts of the P-CSCF 4 as well as other functions in order to, forexample, protect and support the IMS core network 4.

The P-CSCF 4 will as it receives the SIP invite message from theterminal UE A anchor the call in the MP 5, by ordering the MPS to addthe terminations or anchoring points T1 and T2 for the call. Anchoringthe call in the MP 5 may be performed in order to prepare for the caseswhere a local media connection is not allowed between the terminals UE Aand UE B. The P-CSCF may forward the SIP invite message to otherrelevant nodes in the IMS core network 2, which may anchor the call inrelevant media plane nodes. Anchoring the call in the relevant mediaplane nodes is also performed in order to prepare for the case where alocal media connection is not allowed between the terminals UE A and UEB.

The P-CSCF 4 will then, based on user configuration informationconfigured in the P-CSCF 4, make a decision whether or not to allow acommunication channel or media signalling path AB1 using a local mediaconnection to be established between the terminals UE A and UE B in theaccess network 1.

If the user configuration information configured in the P-CSCF 4 and/oran internal database does not allow a local media connection AB1, theP-CSCF 4 will further anchor the call in the MP 5 by adding theterminations or anchoring points T3 and T4. The communication channel,or media signalling path, between the terminals UE A and UE B will thenbe set up according to the dashed line AB2 in FIG. 1.

However, should the user configuration information in the P-CSCF 4 allowa local media connection between the terminals UE A and UE B, the P-CSCF4 will send an SIP invite message to the terminal UE B through thecontrol plane path B. The P-CSCF 4 will later also order the MP 5 tosubtract the terminations or anchoring points T1 and T2. A communicationchannel AB1 using a local media connection between the terminal UE A andUE B in the access network 1 may then be established.

It should also be noted, however, that if nodes in the IMS core network2 previously has anchored the call in a media plane node or nodes, thismay be detected by the P-CSCF 4 which may then decide to not apply alocal media connection between the terminal UE A and UE B in the accessnetwork 1.

In order to use the user configuration information located in the P-CSCF4, and/or the A-ALG, for setting up a local media connection AB1requires that the user configuration information frequently has to beupdated. The user configuration information may, for example, comprisecompany employees between which a company may wish to allow local mediaconnection usage of the company's network bandwidth. However, the taskof updating and/or adding to the user configuration information is atime-consuming and complex task. In the case of multiple SBCs, it alsofollows that each of the SBCs has to be individually programmed with theuser configuration information. This also makes it very difficult toallow a local media connection between terminals not sharing the sameSBC. It further also provides SBCs with a high degree of complexity.

According to the inventive features of the present invention, theseissues are addressed in a communication system by SBC and IMS networknodes of which exemplary embodiments are presented in the following. TheSBC and IMS network nodes coordinate user configuration informationregarding a local media connection between SBC and IMS network nodes,reduce the complexity of the SBC, reduce the use of system resources inthe networks, as well as, allow each network node to focus on itsdedicated tasks.

FIG. 2 illustrates an IP based communication system comprising networknodes arranged with the inventive features of the present invention. Theterminals UE A and UE B are located within an access network 1 of an IPbased communication system. The access network 1 is arranged tocommunicate with a Session Border Controller (SBC) 3. However, the innerstructure and details of the access network 1 of the IP basedcommunication system is not relevant to the object of the presentinvention. Therefore, no further description of the access network 1 isconsidered necessary in describing the inventive features of the presentinvention.

The IMS core network 2 in FIG. 2 comprises essentially the same nodes asillustrated in the simplified example of the IMS core networkarchitecture in FIG. 1. Although, it should be noted that for sake ofsimplicity and relevance to the purpose of the present invention onlythe inventive features of the nodes S-CSCF 6 and AS 7 will be discussedbelow in reference to the IMS core network 2.

The SBC 3 in FIG. 2 comprises essentially the same nodes as illustratedin reference to prior art in FIG. 1. However, the SBC 3 in FIG. 2according to the present invention may be arranged to, instead of beingconfigured with user configuration information as in prior art, send amessage or request through the S-CSCF 6 to the AS 7 in the IMS corenetwork 2 requesting to know whether or not a local media connection AB1is allowed between a first terminal UE A and at least a second terminalUE B.

In IMS core networks, application servers are SIP entities that hostsand executes various services. The application servers may be configuredwith data related to a user, or be arranged to download or upload datarelated to a user stored in, for example, an HSS12. It is often the taskof application servers to keep track of different user groups and theusers belonging thereto. The application server AS 7 can therefore inaccordance with the present invention be arranged with the userconfiguration information relating to a local media connection betweenusers in the access network 1. It follows that the AS 7 may be arrangedto, for example, upon request look up or check within its comprised userconfiguration information if a local media connection between twoterminals is allowed. Alternatively, the AS 7 may be arranged to uponrequest upload the relevant user configuration information concerning alocal media connection between two terminals from other network nodes,for example, the HSS12. The application server AS 7 provides a moreefficient, flexible and simpler solution to allow a local mediaconnection between a first UE A and at least a second terminal UE B inthe access network 1. The AS 7 may be easily kept up-to-date by theoperator, which no longer has to individually program each SBC. The AS 7may also be a “business trunking” application server.

The AS 7 may further be arranged to insert a “local media” header in SIPmessages. The “local media” header may inform a requesting network node,for example, the P-CSCF 4 in the SBC 3, about the local media connectionstatus between two determined terminals in access networks. The localmedia connection status may for example indicate that a local mediaconnection is allowed between a first and at least a second terminal, orthat a local media connection is not allowed between a first and atleast a second terminal. The “local media” header may, for example, be aflag set in the SIP message header or a new line in the SDP part of theSIP message. By standardizing and incorporating a “local media” headerin the SIP signalling, application servers, ASs, and session bordercontrollers, SBCs, from different vendors may be provided with thepossibility to work together to apply a local media connection.

The S-CSCF 6 in the IMS core network 3 may be arranged to receive SIPmessages that include “local media” headers from the AS 7 and the P-CSCF4. If the terminal UE B is in the same network as the terminal UE A, theS-CSCF 6 may be arranged to forward SIP messages comprising “localmedia” headers to the AS 7 from the P-CSCF 4 in the SBC 3, and viceversa. However, if the terminal UE B is associated to another IMS corenetwork or in, for example, another access network than the terminal UEA, the S-CSCF 6 may be arranged to forward SIP messages comprising“local media” headers to/from the P-CSCF currently associated with theterminal UE B. The P-CSCF currently associated with the terminal UE Bmay not be the same as the P-CSCF 4 associated with the terminal UE A.

As is illustrated by the control signal path C in FIG. 2, the presentinvention may coordinate user configuration information regarding alocal media connection between the SBC 3 and nodes in the IMS corenetwork 2. The control signal path C and the signalling that occursbetween the SBC 3 and the nodes in the IMS core network 2 will bedescribed in more detail in the following with reference to FIGS. 3 and4.

FIG. 3 is a flowchart illustrating an exemplary operation of a sessionborder controller, SBC 3, and network nodes, S-CSCF 6 and AS 7,according to the present invention. A first terminal, for example, theterminal UE A, in the access network 1 attempts a call to a secondterminal, for example, the terminal UE B. The call may be an ordinaryvoice call or a multimedia call comprising both audio and video. Theterminal UE B may be located in the same or in another access network 1.An invite, for example, a SIP invite message with an SDP offer, is thensent on the control plane from the first terminal UE A to the SBC 3. Theinvite is received by the SBC 3.

In step S31, the SBC 3 receives the invite from the first terminal UE Ato the second terminal UE B. In step S32, since no user configurationinformation concerning a local media connection is configured in the SBC3, the SBC 3 sends a message or request to an application server AS 7 ina multimedia core network, e.g. the IMS core network 2, requestinginformation regarding whether or not a local media connection is allowedbetween the first terminal UE A and the second terminal UE B. The AS 7receives the message or request from the SBC 3.

In step S33, the AS 7 looks up or checks within its comprised oruploaded user configuration information if a local media connection isallowed between the first terminal UE A and the second terminal UE B. Instep S34, the AS 7 returns a message to the SBC 3 indicating the localmedia connection status between the first terminal UE A and the secondterminal UE B. The SBC 3 receives the message from the AS 7.

In step S35, the SBC 3 determines from the information comprised in themessage from the AS 7 whether or not a local media connection is allowedbetween the first terminal UE A and the second terminal UE B. If a localmedia connection is allowed between the first terminal UE A and thesecond terminal UE B, the SBC 3 will in step S36 perform signalling thatestablishes a communication channel that uses a local media connectionbetween the first terminal UE A and the second terminal UE B.Alternatively, if a local media connection is not allowed between thefirst terminal UE A and the second terminal UE B, the SBC 3 will in stepS37 perform signalling that establishes an anchored communicationchannel between the first terminal LIE A and the second terminal UE B.The communication channel, or media signalling path, will then be set upaccording to the dashed line AB 2 in FIGS. 1 and 2 between the firstterminal UE A and the second terminal UE B. Anchoring the communicationchannel in the SBC 3 forces the call media to pass through SBC 3 betweenthe first terminal UE A and the second terminal UE B.

FIG. 4 is a signalling diagram illustrating in more detail thesignalling between terminals (UE A and UE B), session border controllerunits (P-CSCF 4 and MP 5), and IMS core network nodes (S-CSCF 6 and AS7), according to an exemplary embodiment of the present invention.

The terminal UE A attempts a call to terminal UE B, whereby the terminalUE A sends a SIP invite message 41 with an SDP offer to the P-CSCF 4, orA-ALG, in the SBC 3. It should be noted that, in general and if nothingelse is described, the offer/answer procedure of the SDP (SessionDescription Protocol) is adhered to in the signalling below. Informationabout SDP and the offer/answer procedure can be found in, for example,RFC 4566.

The P-CSCF 4 in the SBC 3 may order 42 the MP 5 to add the terminationsor anchoring points T1 and T2 for the call. The termination T2 may alsoinclude a media address and port number (MPA). Anchoring the call in theMP 5 may be performed in order to prepare for the cases where a localmedia connection is not allowed between the terminals UE A and UE B. TheMP 5 adds the terminations T1 and T2 and may then respond to the message42 from the P-CSCF 4 with a reply message 43 informing the P-CSCF 4 thatthe terminations T1 and T2 has been added for the call. The P-CSCF 4 maythen store, in an internal database, the media addresses and ports ofeach media stream in the SDP offer received in the SIP invite message 41from the terminal UE A, together with the corresponding values of theMPA of the termination T2 and an outgoing session ID.

The P-CSCF 4 then sends a SIP invite message 44 to the S-CSCF 6 in theIMS core network 2. The S-CSCF 6 forwards the SIP invite message 45 tothe application server AS 7 in the IMS core network 2. The AS 7, orother IMS core network nodes such as, for example, the MGC 8, may thenanchor the call in the relevant media plane nodes in order to be able toprovide media services, for example, in the case when a local mediaconnection is not allowed between the terminals UE A and UE B.

As the AS 7 receives the SIP invite message 45, the AS 7 checks withinits comprised or uploaded user configuration information if a localmedia connection is allowed between the terminals UE A and UE B. If alocal media connection is allowed, the AS 7 may insert a local mediaheader, indicted in FIG. 4 by “Local media”, before sending the SIPmessage 46 back to the S-CSCF 6.

S-CSCF 6 sends SDP offer 47 back to AS 7. If the terminal UE B iscurrently served by the same P-CSCF 4, or A-ALG, as the terminal UE A,the SIP message 48-49 including the local media header may be forwardedback to the P-CSCF 4. However, in the case of the terminal UE B beingassociated with, for example, another IMS core network or another accessnetwork, the SIP message 47 including the local media header may beforwarded to the P-CSCF currently associated with the terminal UE B. Thesignalling messages 47-48 indicated by the area inside the dashed lines,may also be performed as part of the standard signalling between thecore network nodes in the IMS core network 2.

The P-CSCF 4 inspects the received SIP message 49. If the SIP message 49includes a local media header or a local media header indicates that alocal media connection is allowed between the terminals UE A and UE B,the P-CSCF 4 may decide if a local media connection is to be establishedbetween the terminals UE A and UE B. The P-CSCF 4 may compare the mediaaddress and port number in the received SDP offer in the SIP message 49with its outgoing SDP offers stored in the internal database of theP-CSCF 4. The P-CSCF 4 is then able to recreate the SDP offer itreceived in the SIP invite message 41 from the terminal UE A, since theoutgoing and the received SDP offers are stored together in the internaldatabase. The P-CSCF 4 may then, by using the stored SDP offers in theinternal database, recreate the SDP offer it received in the SIP invitemessage 41 from the terminal UE A and send a SIP invite message 410 tothe terminal UE B. However, the P-CSCF 4 does not include the localmedia header in the SIP message 410 in order not to disclose thisinformation to the terminal UE B. This may be performed in order to notsend unnecessary information to the terminal UE B, and for varioussecurity aspects. The P-CSCF 4 also does not order the MP 5 to add theterminations T3 and T4 for a terminating call leg, as it would haveshould a local media connection not be allowed between the terminals UEA and UE B.

It should also be noted that should the SIP message 49 not include alocal media header, or include a local media header indicating that alocal media connection is not allowed between the terminals UE A and UEB, the P-CSCF 4 will go ahead and anchor a communication channel for thecall in the MP 5 in the SBC 3. This procedure is not shown in FIG. 4since it is part of the prior art and therefore can be consideredcomprised in the already existing design base.

The terminal UE B may respond to the SIP invite message 410 with a 200OK message 411 including an SDP answer.

Since a local media connection is to be applied, the P-CSCF 4 forwardsthe SDP answer unmodified in a 200 OK message 412 to the S-CSCF 6, butincludes the local media header to indicate to the originating side,that is, the terminal UE A, that a local media connection is to beapplied. In order to cater for possible forking scenarios, the P-CSCF 4may also enter the SDP answer in its internal database.

S-CSCF 6 forwards the SDP answer in a 200 OK message 413 to the AS 7.The AS 7 then sends the SDP answer in a 200 OK message 414 back to theS-CSCF 6. The S-CSCF 6 returns the SDP answer in a 200 OK message 415 tothe AS 7. The AS 7 then sends the SDP answer in a 200 OK message 416-417to the P-CSCF 4, which receives the SDP answer for the originating sideof the call. The signalling messages 413-417 is performed as part of thestandard signalling between the core network nodes in the IMS corenetwork 2.

The P-CSCF 4 receives the SDP answer in the 200 OK message 417 andchecks if the local media header is included. By checking in itsinternal database, the P-CSCF 4 knows to which streams a local mediaconnection shall be applied. The P-CSCF 4 then sends the SDP answer,from the terminal UE B, in the 200 OK message 418 to terminal UE A,which completes the offer/answer procedure between the terminals UE Aand UE B. Thereby, the media call 419 is set up, and call media can nowfloat along the local media connection path AB1 in FIG. 2.

Since a local media connection has been applied between the terminalsUEA and UEB, the P-CSCF 4 may order 420 the MP 5 to release the unusedterminations T1 and T2 for the originating side of the call, i.e. theoriginating call leg. The MP 5 may then subtract the terminations T1 andT2 and send back an acknowledgement 421 to the P-CSCF 4.

The present invention may by not having the SBCs configured with theuser information reduce the complexity of a session border controllerunit P-CSCF 4 (or A-ALG), in a session border controller (SBC 3). Thissince the configuration information that allows a local media connectionin a communication system from the session border controller unit P-CSCF4 (or A-ALG) is removed. Instead, by locating said configurationinformation in an application server AS 7, the task of updating andadding to the user configuration information is made much simpler forsystem operators and administrators. The present invention also removesthe need to, in the case of multiple SBCs, individually program each ofthe SBCs with the user configuration information.

By performing the method of the present invention the use of systemresources in the core networks of the communication system is reduced,since the configuration information is more easily kept up-to-date andtherefore may allow more communication channels using a local mediaconnection to be established.

The present invention does also include a computer program product foruse in a session border controller unit 4, which comprises computerreadable code means, which when run in the session border controllerunit 4, causes said session border controller unit 4, to make a decisionwhether a local media connection AB1 between a first terminal UE A andat least a second terminal UE B should be established in an accessnetwork 1 based on information established by and received from anapplication server 7 in said multimedia core network 2.

The computer program product can also comprise computer readable codemeans, which when run in the session border controller unit 4 causes thesession border controller unit 4 to, upon receiving a call invitationfrom said first terminal UE A to said second terminal UE B, forwardinformation associated with said call invitation to said applicationserver 7.

The computer program product can further comprise computer readable codemeans, which when run in the session border controller unit 4 causes thesession border controller unit 4 to, if said information from saidapplication server 7 indicates that a local media connection is allowedbetween said first terminal UE A and at least second terminal UE B,establish a local media connection AB1 between said first terminal UE Aand at least second terminal UE B terminal.

The computer program product can also comprise computer-readable codemeans, which when run in the session border controller unit 4 causes thesession border controller unit 4 to, if said information from saidapplication server 7 indicates that a local media connection is notallowed between said first terminal UE A and at least second terminal UEB, establish a communication channel AB2 between said first terminal UEA and at least second terminal UE B anchored in the session bordercontroller 3.

The code means for the computer program is stored on a readable storagemedium.

The description above is of the best mode presently contemplated forpractising the present invention. The description is not intended to betaken in a limiting sense, but is made merely for the purpose ofdescribing the general principles of the invention. The scope of thepresent invention should only be ascertained with reference to theissued claims.

1. A method for deciding whether a local media connection should beestablished in an access network of an IP-based communication systembetween a first terminal and at least a second terminal located withinsaid access network, wherein said access network is connected to asession border controller (SBC) providing access to a multimedia corenetwork, the method comprising the steps of: receiving, in the sessionborder controller, a call invitation from the first terminal to the atleast second terminal; sending, from the session border controller to anapplication server in a multimedia core network, a message requesting alocal media status between the first terminal and the second terminal;checking, by the application server, if a local media connection isallowed between the first terminal and the second terminal; receiving,in the session border controller from the application server, a messageindicating the local media status between the first terminal and thesecond terminal, and further indicating whether a local media connectionis allowed between said first terminal and the second terminal; if themessage indicates that a local media connection is allowed,establishing, by the session border controller, a local media connectionbetween said first terminal and at least the second terminal; and if themessage indicates that a local media connection is not allowed,establishing, by the session border controller, a communication channelbetween said first terminal and at least the second terminal anchored ina media proxy in said session border controller.
 2. The method accordingto claim 1, wherein said information is established by said applicationserver based upon information associated with a call invitation fromsaid first terminal to said second terminal, received from said sessionborder controller unit.
 3. A session border controller unit (SBC) fordeciding whether a local media connection should be established in anaccess network of an IP-based communication system between a firstterminal and at least a second terminal located with said accessnetwork, wherein said session border controller is connected to saidaccess network and a multimedia core network, the session bordercontroller comprising: processing circuitry configured to receive, acall invitation from the first terminal to the at least second terminal;the processing circuitry further configured to send to an applicationserver in a multimedia core network, a message requesting a local mediastatus between the first terminal and the second terminal; and theprocessing circuitry further configured to receive from the applicationserver, a message indicating the local media status between the firstterminal and the second terminal, after the application server haschecked if a local media connection is allowed between the first andsecond terminal, and further indicating whether a local media connectionis allowed between said first terminal and the second terminal; if themessage indicates that a local media connection is allowed, theprocessing circuitry configured to establish a local media connectionbetween said first terminal and at least the second terminal; and if themessage indicates that a local media connection is not allowed, theprocessing circuitry configured to establish a communication channelbetween said first terminal and at least the second terminal anchored ina media proxy in said session border controller.
 4. The session bordercontroller unit according to claim 3, further being arranged to, uponreceiving a call invitation from said first terminal to said secondterminal, forward information associated with said call invitation tosaid application server.
 5. An application server in a multimedia corenetwork, being arranged to process information in order to establishwhether a local media connection is allowed between a first terminal andat least a second terminal in an access network of an IP-basedcommunication system, the application server comprising: processingcircuitry configured to receive, from a session border controller, amessage requesting a local media status between the first terminal andthe second terminal, wherein the message is received in response to thesession border controller receiving a call invitation from the firstterminal to the at least second terminal; the processing circuitryfurther configured to check if a local media connection is allowedbetween the first terminal and the second terminal; and the processingcircuitry further configured to send, to the session border controller,a message indicating the local media status between the first terminaland the second terminal, and further indicating whether a local mediaconnection is allowed between said first terminal and the secondterminal; wherein, if the message indicates that a local mediaconnection is allowed, the session border controller establishes a localmedia connection between said first terminal and at least the secondterminal; and wherein, if the message indicates that a local mediaconnection is not allowed, the session border controller establishes acommunication channel between said first terminal and at least thesecond terminal anchored in a media proxy in said session bordercontroller.
 6. The application server according to claim 5, wherein saidinformation is information associated with a call invitation from saidfirst terminal to said second terminal.
 7. The application serveraccording to claim 6, wherein said information associated with the callinvitation from said first terminal to said second terminal, is receivedfrom a session border controller unit.
 8. The application serveraccording to claim 5, further being arranged to retrieve informationregarding whether a local media connection is allowed between a firstterminal and at least a second terminal, from other multimedia corenetwork nodes or external content servers.
 9. The application serveraccording to claim 5, further being arranged to include informationregarding whether a local media connection is allowed between a firstterminal and at least a second terminal, in a message to a sessionborder controller unit.
 10. The application server according to claim 9,wherein said information may be included in the message by using a localmedia header comprising a set flag.